Add lt_dyn_scalar and tests

Author: matthewmturner

arrow/src/compute/kernels/comparison.rs

@@ -1121,6 +1121,42 @@ where
     }
 }
 
+/// Perform `left < right` operation on an array and a numeric scalar
+/// value. Supports PrimitiveArrays, and DictionaryArrays that have primitive values
+pub fn lt_dyn_scalar<T>(left: Arc<dyn Array>, right: T) -> Result<BooleanArray>
+where
+    T: TryInto<i128> + Copy + std::fmt::Debug,
+{
+    match left.data_type() {
+        DataType::Dictionary(key_type, value_type) => match value_type.as_ref() {
+            DataType::Int8
+            | DataType::Int16
+            | DataType::Int32
+            | DataType::Int64
+            | DataType::UInt8
+            | DataType::UInt16
+            | DataType::UInt32
+            | DataType::UInt64 => {dyn_compare_scalar!(&left, right, key_type, lt_scalar)}
+            _ => Err(ArrowError::ComputeError(
+                "Kernel only supports PrimitiveArray or DictionaryArray with Primitive values".to_string(),
+            ))
+        }
+        DataType::Int8
+        | DataType::Int16
+        | DataType::Int32
+        | DataType::Int64
+        | DataType::UInt8
+        | DataType::UInt16
+        | DataType::UInt32
+        | DataType::UInt64 => {
+            dyn_compare_scalar!(&left, right, lt_scalar)
+        }
+        _ => Err(ArrowError::ComputeError(
+            "Kernel only supports PrimitiveArray or DictionaryArray with Primitive values".to_string(),
+        ))
+    }
+}
+
 /// Perform `left == right` operation on an array and a numeric scalar
 /// value. Supports StringArrays, and DictionaryArrays that have string values
 pub fn eq_dyn_utf8_scalar(left: Arc<dyn Array>, right: &str) -> Result<BooleanArray> {
@@ -2973,6 +3009,33 @@ mod tests {
         );
     }
     #[test]
+    fn test_lt_dyn_scalar() {
+        let array = Int32Array::from(vec![6, 7, 8, 8, 10]);
+        let array = Arc::new(array);
+        let a_eq = lt_dyn_scalar(array, 8).unwrap();
+        assert_eq!(
+            a_eq,
+            BooleanArray::from(
+                vec![Some(true), Some(true), Some(false), Some(false), Some(false)]
+            )
+        );
+    }
+    #[test]
+    fn test_lt_dyn_scalar_with_dict() {
+        let key_builder = PrimitiveBuilder::<Int8Type>::new(3);
+        let value_builder = PrimitiveBuilder::<Int32Type>::new(2);
+        let mut builder = PrimitiveDictionaryBuilder::new(key_builder, value_builder);
+        builder.append(123).unwrap();
+        builder.append_null().unwrap();
+        builder.append(23).unwrap();
+        let array = Arc::new(builder.finish());
+        let a_eq = lt_dyn_scalar(array, 123).unwrap();
+        assert_eq!(
+            a_eq,
+            BooleanArray::from(vec![Some(false), None, Some(true)])
+        );
+    }
+    #[test]
     fn test_eq_dyn_utf8_scalar() {
         let array = StringArray::from(vec!["abc", "def", "xyz"]);
         let array = Arc::new(array);